Tracheostomy and Personal Protective Equipment (PPE) in the midst of the COVID-19 Pandemic - B-ENT
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REVIEW
DOI: 10.5152/B-ENT.2020.20128
Tracheostomy and Personal Protective Equipment
(PPE) in the midst of the COVID-19 Pandemic
Callum Faris1,2 , Kristof Deben3 , Gilles van Haesendonck1,2 , Carl Van Laer1,2 , Roberto Puxeddu4 , Katia Verbruggen5 , Steven Mariën1,2 ,
Frans Gordts5 , Navin Mani6 , Olivier M. Vanderveken1,2
1
Department ENT and Head Neck Surgery, Antwerp University Hospital, Antwerp, Belgium
2
Translational Neurosciences, Faculty of Medicine and Health Sciences, University of Antwerp, Antwerp, Belgium
3
Department of Otorhinolaryngology and Head and Neck Surgery, Jessa Hospital Campus Virga Jesse, Hasselt, Belgium
4
Department of Otorhinolaryngology, University of Cagliari School of Medicine, Cagliari, Italy
5
Department of Otorhinolaryngology and Head and Neck Surgery, Universitair Ziekenhuis Brussel and Vrije Universitair Brussel, Brussels, Belgium
6
Central Manchester University Hospitals, University of Manchester, Manchester, UK
Cite this article as: Faris C, Deben K, van Haesendonck G, et al. Making sense of personal protective equipment PPE and tracheostomy in
the mists of the 2020 COVD-19 crisis. B-ENT 2 May 2020. 10.5152/B-ENT.2020.20128 [Epub Ahead of Print]
ABSTRACT
The primary aim was to review the guidelines published by Otolaryngology Societies for performing tracheostomies in the COVID-19 pan-
demic. A secondary aim was to briefly review the literature for the effectiveness of surgical masks, N-95 and FFP-3 respirators, and power air
purifying respirators (PAPRs) in reducing transmission of respiratory viral infections to health care workers while performing tracheostomy.
Recommendations are mainly derived from clinical case series/retrospective observational studies from the SARS 2003/2004 outbreaks or
experimental evidence for effectiveness for N-95/FFP-3 respirators and PAPRs. Differences do occur due to lack of evidence for COVID-19
as to whether N-95 and FFP-3 respirators are sufficient, or PAPRs should be recommended for tracheostomy. We would recommend adopt-
ing a conservative (protective) approach for HCWs teams performing tracheostomies, by routinely utilizing additional PPE such as PAPRs.
Recommendations for the timing of tracheostomy also varied, however, almost all recommend a period of delay. The optimum duration of
which is still unclear.
Keywords: Coronavirus, nosocomial infection, personal proactive equipment, tracheostomy
Introduction patients (80.9%) with COVID-19 are considered asymptomatic
or have symptoms consistent with mild pneumonia (7). Sim-
On December 8, 2019, the onset of symptoms in the first known ilar viral loads have been detected in both asymptomatic and
case of pneumonia with unknown aetiology was observed in mildly symptomatic patients, suggesting transmission potential
Wuhan City, Hubei Province, China. By December 31, 2019, Chi- for the asymptomatic patient (8). Clinical reports are now also
na reports a cluster of 27 cases of pneumonia with unknown emerging of possible transmission in asymptomatic patients (9).
aetiology in Wuhan to the World Health Organization (WHO) Due to these factors, methods of COVID-19 detection and iso-
(1). On January 7th, 2020, a new virus was identified by Chinese lation will need to be modified from those of SARS and MERS
scientists as a novel single-strand, positive-sense RNA coro- (10). In part, due to these differences in clinical progression, the
naviruses (1). By January, the 30th, 2020, WHO declared a glob- COVID-19 outbreak has shown an uncontrolled exponential rise,
al alert over concerns of a SARS type infection (1) and on 11th unlike MERS or SARS, which were contained. There are currently
March 2020, the WHO declared a global pandemic. At the time confirmed 1.982.939 million affected and 126.761 deaths, with
of writing this article, we are currently in the midst of a global continued difficulties in containing the virus resulting in a glob-
pandemic due to this novel coronavirus (COVID-19). It primari- al pandemic (source: John Hopkins University, Coronavirus re-
ly affects the respiratory tree producing a SARS MERS type ill- source centre: https://coronavirus.jhu.edu/map.html).
ness (2-4). Initial experience from China suggested a less-lethal
disease (COVID-19 mortality 3.17%) (5) than the SARS (2004 Nosocomial infection of health care workers (HCWs) is a se-
- 9.6%) or MERS (2009 - 35%) outbreaks (6). The majority of rious concern with SARS types of viruses (SARS, MERS). The
Corresponding Author: Callum Faris; callum.faris@uza.be
Received: April 21, 2020 Accepted: April 23, 2020 Available Online Date: May 2, 2020
Available online at www.b-ent.be
CC BY 4.0: Copyright@Author(s), “Content of this journal is licensed
under a Creative Commons Attribution 4.0 International License.”
Faris et al. Review of Tracheostomy and personal protectieve equipment PPE in COVID-19 patients B-ENT 2020 Canadian SARS outbreak in 2003 resulted in 438 cases, with The basic reproduction number (R0) 51% of these being HCWs, 3 of whom died (11). In Hong Kong, The basic reproduction number is used in infectious disease over 400 out of 1755 SARS patients were HCWs (12). Unfor- epidemiology to describe how transmissible a specific infec- tunately implementing infection control measures are not tion is. The value of R is the average number of new infections fail-safe with nosocomial infection of HCWs continuing, de- attributed to a single infectious person. When R>1 the number spite measures (13). The high rate of transmission to HCWs of cases will increase, and for R
B-ENT 2020 Faris et al. Review of Tracheostomy and personal protectieve equipment PPE in COVID-19 patients
Surge capacity and adherence to hand hygiene protocols are vital to reduce
Refers to the capacity of a facility to manage a sudden, un- contamination (19).
expected increase in patient volume that would otherwise
severely challenge or exceed the present capacity of a facili- Eye Protection Visors and Face Shields
ty (26). Conventional capacity describes the ability to provide One study examined eye protection during orthopaedic sur-
gery, making comparisons of several types of eye protection.
patient care without any change in standard daily practices
Contamination rates showed that normal eyeglasses were no
(e.g. recommended PPE and general infection prevention) in
better than controls, loupes had a 50% contamination rate and
healthcare settings. Contingency capacity describes a change
surgical mask with an integrated visor had 30% contamination
in daily contemporary practices that may not have any signif-
rate. Best protection rates were provided by wrap-round plas-
icant impact on the care delivered. Crisis capacity denotes a
tic disposable glasses, most similar to goggles (28). One study
significant departure from contemporary standards of care
comparing full-face shield versus safety glasses in combina-
(26).
tions with N95 respirators found full-face shield combinations
Personal Protective Equipment (PPE) with N95 gave the greatest protection (29).
This includes the following Full-face shields should have dimensions that extend to the
• Respirator or reusable respirators (e.g., powered air-purify- bottom of the chin, and a face/neck length that also covers the
anterior neck area. Most visors curve around the face and the
ing respirators (PAPRs))
recommendations from the Center for Disease Control and
• Eye protection goggles, disposable full-face shield
Prevention (CDC) are visors should reach from ear to ear. Max-
• Gloves
imum protection is therefore afforded by the combination of
• Gowns
respirator + full-face shield or goggles. Safety glasses, loupes,
• Surgical cap (27)
normal glasses are not advised (30).
Gloves
Surgical Masks
Gloves act as a physical barrier between contaminated surfac-
Surgical masks (SMs) are effective for reducing transmission
es and the skin. They also can help the individual as a reminder
for droplets, splashes and sprays that may contain viruses and
to avoid self-inoculation. Changing gloves between patients bacteria. SMs do not create a tight seal against the skin leading
to air influx around the SM. Thus, the filtration or fit is not ad-
equate to prevent inhalation of small particles. The protection
factor of face masks against particles (0.04-1.3 μm) was on
average of 8 to 12 times less than N95 respirators (31). SMs
are therefore used only as for protection from infectious fluids
(droplets, splashes, or sprays).
Respirators (FFP2, FFP3 N95), the fit-test and its relevance
The certifications between the USA and Europe differ. The
National institute for occupational safety and health (NIOSH)
certified N95, N99, N100 respirators (N=not for use in an oil
droplet environment) to have a minimum efficiency of filtra-
tion of fine particles (NaCl approximately 300 nm) of 95%,
99% and 99.97% respectively (19, 32). Further studies have
shown the efficacy of N95 to filtering aerosol particles in the
4-30 nm range (33), which is smaller than COVID-19 at 70-
90 nm (34). The European Standard (EN 149:2001) classifies
three classes again using NaCl particles: FFP1, FFP2, and FFP3
with a minimum efficiency of 80 and 94% and 99% respec-
tively. However, a high filtration efficiency alone does not en-
sure protection. The particle influx through face seal leakage
of the N95 respirator far exceeds the influx through the filter.
The ratio of face seal leakage to filter leakage is in the range of
7-20:1, therefore focusing on fit in disposable respirators (N95,
FFP-2/3) is vitally important (35). This point is underscored by
the fact that up to 25% (5-25%) of individuals do not pass a
fit test with the first respirator tried (36, 37). Instructions from
manufactures 3M on how to perform a fit test for an N95 mask
can be found online at https://www.youtube.com/watch?v=x-
l4qX6qEYXU&t=53s.
Figure 1. Maximal PPE for COVID-19 positive suspect Tracheostomy:
double gloves, surgical cap, goggles, disposable waterproof gown, Each time a FFP3 or N95 respirator is worn, a fit-check should
FFP-3 fit tested and PAPR Draeger hood. Consistent with Wuhan be performed. Whilst covering the respiratory with both hands.
level 3 precautions. For a unvalved product, exhale sharply; for a valved product,Faris et al. Review of Tracheostomy and personal protectieve equipment PPE in COVID-19 patients B-ENT 2020
inhale sharply whilst checking for leaks around the respirator. air pressure. The wearers unfiltered exhaled air is also included
Adjust the fit of the nosepiece or straps accordingly (20). in this airflow efflux for the hood, which can, therefore, trans-
mit the infection to other HCWs or the patient. Loose-fitting
Powered Air Purifying Respirators PAPRs do not totally enclose the head, so over-breathing the
SARS transmission has occurred despite the use of N95 respi- air blower (caused by high respiratory rates of the wearer) can
rator during high-risk procedures (24, 38). An alternative PPE occur, leading to possible contamination (43).
to disposable respirators (N95, FFP-2/3) for aerosol precau-
tions is the Powered Air Purifying Respirator (PAPR). It is a bat- Combining an N95 or FFP-3 respirator with a PAPR may be
tery-powered blower that provides positive airflow through a one solution to the over-breathing and exhaled air issues, and
filter to a hood/facepiece/helmet. A common type of PAPR the it also may further increase the APF (38, 43, 45, 46). In exper-
medical setting is the loose fitted hood PAPR. A major benefit imental conditions, the combination of N95 respirator with a
is that there are no requirements for a total seal around the hood PAPR was shown to increase the APF from approximate-
mouth; thus, they do not require fit testing (unlike disposable ly 100 (N95) to 150,000 (combination N95 mask+PAPR) (41).
respirators N95, FFP-2/3). The delivered air is under positive
pressure, and the hood is not sealed. The airflow is continuous The combination of N95 respirator and a hood PAPRs which had
from the blower to the hood, and then the air escapes out of been deactivated (air-purifying motor pump switched off, simu-
the hood to the surrounding. This uni-directional airflow limits lating the loss of power) has also been investigated. Deactivated
entrainment of contaminated air. hood PAPRs used in isolation (without an N95 respirator) tend-
ed to have APFs in the range 4-10, similar in range to Stryker
The type filter can vary, for example, a high-efficiency partic- APF of 3.1 (24), but lower than an N95 respirator (AFP usual-
ulate air (HEPA) filters have a similar filtration rate as a P100 ly>10) (41). Deactivated hood PAPRs+N95 respirators combi-
(99.97% of particles 0.3 μm in diameter). Therefore, a PAPR nations routinely showed large increases in the APF (N95 APF
+ HEPA filter has improved respiratory protection than N95 approximately 100, Deactivated hood PAPRs APF approximately
masks. One such type is the Airmate 3M HEPA (3M, USA) 4-10) to over 1000 (41). Surgical hood (Stryker T4 or other) and
(12, 38, 39). PAPR systems that are in current use during the N95 respirator combinations were not tested (41).
Covid-19 pandemic include the 3M versaflo, which replaces
the Airmate and the Draegar X-plore. A distinction should be Combinations of PAPRs and N95/FFP-3 respirators do have
made with the Stryker T4 surgical hood system (Stryker Cor- drawbacks; communication difficulties, claustrophobia and a
poration, USA) which is not certified as a PAPR. When used in possible higher risk of self-contamination (43). This combina-
isolation, it is less effective at the filtration of nanoparticles tion is also more uncomfortable and cumbersome than using
than an N95 respirator. N95 or FFP-3 respirators or PAPR in isolation.
The assigned protection factor APF denotes the fraction of air- PAPRs can be re-usable, and therefore, suitable decontamina-
borne contaminant present that the individual can expect to tion protocols must be in place if they are to be safely reused
inhale (for example, APF 10=10%, APF 25=4%, APF 100=1%). (46). Due mainly to these decontamination factors, the CDC
It takes into account, in properly fitted and trained users, all recommends disposable filtering facepiece respirators over
expected sources of facepiece penetration (face seal penetra- PAPRs (19).
tion, filter penetration, and valve leakage) (40). The loose-fit-
ting facepiece PAPR has an APF of 25, helmet PAPR has an PAPRs alone or a combination of respirator and PAPR can have
APF of 25, and loose-fitting hood PAPR has an APF of 1000 an advantage in situations where N95 or FFP-3 respirators are
(41, 42). used in non-ideal scenarios (facial hair or failure of a fit test) or
where high-risk AGPs are performed (39, 47).
The Stryker T4 surgical hood has an suggested protection fac-
tor (APF) of 3.1, in comparison to the N95, which has an APF of Correct donning and doffing
greater than 10 (24, 43). However, during quantitative testing, When donning and doffing a correct sequence should be fol-
the average ambient-to-inside device of similar sizes to the lowed to reduce the chances of self-contamination. The indi-
coronavirus was approximately 3.8 (the fit test factor). It per- vidual should be trained in this process and ideally be observed
forming far inferiorly to a N100 respirator and face-shield (44), (buddy to checking) for adherence to the protocol. Recom-
and also lower than what would be expected of a minimum mendation of donning and doffing for PPE (N95/FFP-3) have
of 100 for a pass for an N95 respirator (ten times the APF as been previously published and are included below.
the Fit Factor Pass). It is recommended by the manufactur-
er that Stryker T4 surgical hood system (Stryker Corporation, Before leaving the relevant work area
USA) should not be used alone to protect against transmission • Gloves, gown/apron, and eye protection should be re-
of SARS (44), (available from: URL: http://sars.medtau.org/ moved (in that order, where worn) and disposed of as
strykerreport.doc), and in fact it is not licensed for this pur- healthcare hazard waste.
pose. It is also recommended that its helmet not be used with- • On removal of eye protection, it should be handled by the
out additional eye and respiratory protection in this setting. headband or earpieces only.
• Where non-disposable eye protection has been used, ap-
The disadvantages of PAPRs are several. Donning and doffing propriate measures for decontamination between uses
is more complex, and a set sequence should be followed (45). needs to be in place.
There is an increase chance of contamination of the surgical • Hand hygiene must be performed after removal and dis-
site with air being blow out from under the hood by positive posal.B-ENT 2020 Faris et al. Review of Tracheostomy and personal protectieve equipment PPE in COVID-19 patients
After leaving the area which will remain definitively unanswered until after this pan-
• The respirator or surgical mask can be removed and dis- demic has passed since, for example, the effectiveness of the
posed of as healthcare hazard waste. tracheostomy in ICU for COVID 19 patients is currently unclear.
• Untie or break the bottom ties first, followed by top ties or
elastic, and remove by handling ties only. Should routine PAPR be offered as well as or instead of an
• Hand hygiene must be performed after disposal. (20) N95 or FFP-3 respirator to surgeons performing tracheos-
tomies on COVID-19 positive patients?
An example of a donning and doffing protocols for PAPRs PAPRs are cumbersome and require specific training; howev-
is published for teams (45). Video demonstration of CDC er, they are highly effective in reducing aerosol transmission to
compliant modules for demonstrations of PPE (PAPR and the lungs and droplet transmission to the face and eyes. Hence
gowns combinations) donning https://www.youtube.com/ this decision should be carefully considered.
watch?v=d0lLf63iyPM and also doffing https://www.youtube.
com/watch?v=-X4dNMgFGyo&t=3s from Johns Hopkins For surgeons performing a tracheostomy which is a high-risk
Hospital for the Ebola virus outbreak are available online. APG, a combination of a fit-tested respirator (FFP-3) with a
suitable PAPR can improve protection levels. Alternatively, a
What we know from SARS PAPR (APF of >1000) can be used alone, instead of an FFP-3
Much of the guidance for COVID-19 is based on studies of the respirator to increase the protection level. This recommenda-
SARS experience for the 2003-2004 outbreak. Canadian stud- tion is at the discretion of the surgeon/surgical team. Factors
ies reported that the probability of SARS infection was 6% such as length and complexity of the surgery, viral load, sur-
(8/143) per shift worked and extrapolated that if all nurses had geon tolerance for FFP-3/N95 respirators/ PAPR and the pres-
worked eight shifts, 53% of them would become infected with ence of any pre-existing co-morbidities in the operating team
SARS. Reassuringly almost an 80% reduction in risk for infec- may influence this decision.
tion for nurses who consistently wore either surgical mask or
N95 respirators was reported. out to be more protective than Where a respirator (FFP-3 or N95) is worn without a PAPR,
a surgical mask. However consistent use of an N95 respirator suitable eye protection is mandatory (full face shield or gog-
turned out to be more protective than a surgical mask. (48, 49). gles). Importantly the use of surgical hoods systems (non-PA-
The likely modes of transmission for SARS were interpreted as PRs such as the T4 Stryker system) in isolation (without an
either droplet or limited aerosol generation during AGPs (48- FFP-3/N95 respirator) is not recommended.
50). A systematic review looked at ten studies from the SARS
2003-2004 outbreak to analyse the risks of nosocomial infec- It is likely that non-fit tested respirators (FFP3 or N95) do not
tion to HCWs whilst undertaking AGPs. They found risk could provide sufficient protection for a significant proportion of
be stratified according to the type of AGP. Odds ratios (ORs) for surgeons from COVID-19 aerosols whilst performing high-risk
nosocomial infection were in decreasing order; tracheal intu- AGPs such as tracheostomy. It is the authors’ belief that given
bation OR 6.6 (2.3, 18.9); non-invasive ventilation OR 6.6 (4.1, the current evidence, when the respirator cannot be fit tested
10.6), tracheotomy OR 3.1(1.4, 6.8) and manual ventilation be- or where the surgeon is unable to pass a fit test, a PAPR or
fore intubation with an OR of 2.8 (1.3, 6.4) (16). From this, it can a combination of FFP-3/N95 respirator and PAPRs should be
be concluded that tracheostomy is a high-risk procedure for used as an alternative. This level of precautions (PAPR+FFP-3/
nosocomial infection to HCWs in SARS. This can potentially be N95) is in line with Wuhan level 3 precautions, one of the cen-
extrapolated to other similar respiratory infective viruses such as tres with the most experience in dealing with this pandemic
COVID-19. With regards to AGPs in SARS, N95 respirators may and where it was also effectively contained (46).
not be enough. Transmission may have occurred despite the use
of appropriate respirators during a resuscitation scenario (24), COVID-19 positive PPEs
and transmission occurred in 9 HCWs despite standard PPE
• Double Gloves – aids doffing of PPE reducing the chance
(N95 respirators) in a difficult airway scenario (38).
of self-contamination
Reviewing the literature on SARS tracheostomy demonstrates • Surgical cap
five reports of tracheostomy in SARS patients. They advocat- • Disposable waterproof gown
ed standard PPE (N95 respirator, surgical cap, goggles, surgical • Goggles or a full-face shield
gown) gloves and negative-pressure room in ICU or operating • FFP-3 (fit-tested) absolute minimum
room. One of the main differences was whether they utilised • FFP-3 + hood PAPR recommended
additional PPE, such as PAPR or surgical hood in addition to • Hood PAPR (APF >1000) recommended
N95 respirator was used. In total, 4 of 5 utilised additional PPE
to N95 respirators (12, 38, 45, 51, 52). For non-fit tested FFP-3 or for fit test failures of FFP-3, various
options below are recommended:
Current ENT National Guidelines for Tracheostomy in
COVID-19 crisis (46, 53-61) (Table 2) • Hood PAPR
• FFP-3 non-fit tested + hood PAPR
Discussion
In an emergent situation where a non-fit tested/fit test failed
It is obvious we will be increasingly asked to perform tra- FFP-3 respirator is available but a PAPR is not available the tra-
cheostomies over the coming weeks and months during the cheostomy should be delegated to a colleague with suitable
COVID-19 crisis. Many unanswered questions remain, many of PPE.Faris et al. Review of Tracheostomy and personal protectieve equipment PPE in COVID-19 patients B-ENT 2020
How should we proceed in the clinical setting of a request (Reverse Transcriptase)-PCR vulnerabilities are several; inade-
to perform a tracheostomy in a patient for a non-COVID-19 quate collection, transport and storage interfering substances,
related condition or who has tested COVID negative? manual errors, as sample contamination, testing outside the
The answer relies on the accuracy of COVID-19 test. Are the PCR diagnostic window, use of inadequately validated assays (62).
tests reliable enough to stratify patients into COVID-19 positive These errors can be amplified when lab staff must adapt to
and negative patients prior to performing tracheostomy? work in high-throughput settings in emergencies settings (62).
Some data suggests in adults sensitivity of about 60% with a
At the current time, it is not clearly understood what the ac- false-negative rate of 30-40% (63). As an alternative, a symp-
curacy of the PCR test for COVID-19 is. The potential for RT tom-based and PCR-test strategy is also flawed due to the fact
Table 2. Tracheostomy in COVID-19 Positive Ve Patient Guidelines
Preferred
Method Open/ Eye Aerosol
Percutaneous Protection HAT/CAP Gown Gloves Protection
AMERICAN ACADEMY No Preference Adequate Adequate Adequate Adequate N95
ORL AND HEAD NECK PPE PPE PPE PPE
SURGERY
AAO-HNS
ENT-UK Local Factors, Surgical No Fluid Yes FFP-3
Competencies, Mask Comment Resistant Consider PAPR
And Experience Integrated Disposable Double Optional
Visor Gown Gloving
-Full Face
Shield
CANADIAN SOCIETY Open Yes Yes Yes Yes N95 and/or
OF OTOLARYNGOLOGY Full Aerosol Full Aerosol Full Aerosol Full Aerosol PAPR
AND HEAD AND NECK Ppe PPE PPE PPE
SURGERY Including Including Including Including
CSO-HNS Papr PAPR PAPR PAPR
NETHERLANDS No Preference -Goggles Full PPE Full PPE Full PPE FFP-2
NERTHELANDS SOCIETY -Full Face Protocol Protocol Protocol
FOR ENT AND HEAD Shield According to According to According to
AND NECK SURGERY The Hospital The Hospital The Hospital
Guideline Guideline Guideline
FIRST AFFIATED No Preference -Goggles Yes Fluid Yes N95 and/or
HOSPITAL -PAPR Resistant Double PAPR
Gloving CHINA
ROYAL BELGIUM Both Suitable -Surgical Yes Fluid FFP-2/3 FFP-2/3
ORL AND Risk of Shedding Mask with Resistant
CERVICOFACIAL Appears to Integrated
SURGERY Be Smaller In Visor
Percutaneous -Goggles
But Risk For The -Full Face
Bronchoscopic Shield
Controller
FRENCH SOCIETY OF Not Stated Protective Not Stated Not Stated Not Stated FFP-2
ORL/PEDATRICS Glasses + Consider
SFORL Transparent
PEDATRIC GUIDLINES Sterile Drapes
Over Operative
Field
AUSTRALIA SOCIETY Not Stated Face Shield Yes Fluid Yes N95
ORL AND HEAD NECK Resistant
SURGERY Disposable
ASOHS Gown
ITALIAN ORL AND HEAD Not Stated Face Shield Yes Fluid Yes FFP-3
NECK SURGERY Resistant
Disposable
GownB-ENT 2020 Faris et al. Review of Tracheostomy and personal protectieve equipment PPE in COVID-19 patients
that a significant proportion of patients are asymptomatic de- • PAPR + FFP-3 could be used to decrease the chance of
spite being in the infective viral shedding phase (1). There are at transmission from the wearer to the patient/surgical team
least two time points in the disease course where false nega- at the expense of loss of comfort for the surgeon. How-
tives can occur due to viral loads below the analytical sensitivity ever, if a significant leak is present, this advantage of the
of some RT-PCR assays. At the initial phase of infection of the combination may be lost.
infection, especially in asymptomatic or mildly symptomatic pa-
tients. Subsequently, a second period in the tail of the infection, What is the best procedure percutaneous or open trache-
where the patient is now asymptomatic, but the virus shedding ostomy?
may still persist (62). Incorporating chest CT scans into preop- The previous reports of tracheostomy patients in SARS all
erative screening is likely to improve the accuracy of testing as focus on open procedures (12, 38, 45, 51, 52). In general, the
it has a reported sensitivity of over 90% (64). Importantly, from technique differs from a normal tracheostomy in that the
two-thirds to over 90% of all patients whose RT-PCR became patient is fully paralysed so the ventilation can be controlled.
positive for SARS- CoV-19 after an initially negative test result The tracheostomy then placed only during apnoea, reducing
the aerosol normally produced with the standard technique. A
had CT features suggestive of COVID-19, with a mean interval
well-designed step-by-step protocol for open tracheostomy
period of 5.1±1.5 days for turning positive (64).
has been devised by ENT-UK, abridged summary below (54).
Best Practice Tips Regarding Pre-op Screening COVID-19 Sta-
1. Complete paralysis of the patient throughout the proce-
tus Unknown
dure to prevent coughing and to control ventilation
• Know your local unit’s PCR test for COVID-19 and its 2. Pre-oxygenate with PEEP then stop ventilation
false-negative rate. Are they using the CDC or WHO rec- 3. Advance cuff beyond planned tracheal window site
ommended (RT-PCR) diagnostic assay? Has it been vali- 4. Stop ventilation and allow time for passive expiration with
dated? open APL valve
• Provide clear instructions on how nasopharyngeal and oro- 5. Create tracheal window preserving the cuff, deflate cuff
pharyngeal swabs should be collected and delivered to the then withdraw ET tube proximal to the tracheal window.
lab – poor sampling can result in false negatives. 6. reducing the use of suction during the procedure, if used,
• Serial testing minimum of two, especially if negative this should be within a closed system with a viral filter.
RT-PCR test results and high suspicion or probability of 7. Insert cuffed, non-fenestrated tracheal tube with
COVID-19 infection infection, utilise CT-scan of the lung non-fenestrated inner tube
if possible (see below). 8. Immediately inflate tracheostomy tube cuff and place an
• Consider associated symptoms compatible with HME with attachment to the circuit, Resume ventilation
COVID-19. Treat as confirmed COVID-19 positive if high 9. Confirm position with end-tidal CO2, and then withdraw
clinical suspicion or high chance of exposure, utilise CT- clamped ETT carefully
scan of the lung (see below). 10. Avoidance of monopolar diathermy which risks further
• CT-scan of the lung, typical findings of infection include; aerosolization of the virus
ground-glass opacities, consolidation, air bronchogram
Full guidance protocol can be found at https://www.entuk.org/
signs and interlobular septal thickening. Ideally, CT chest
sites/default/files/files/COVID%20tracheostomy%20guid-
can be combined with CT for mastoiditis, complicated si-
ance_compressed.pdf
nusitis, neck abscess). If a CT scan is positive, treat as con-
firmed COVID-19 positive even with a negative RT-PCR Percutaneous tracheostomy techniques have also been
test. adapted to be performed under full paralysis and apnoeic
conditions to decrease the risk of viral aerosol. When per-
It is practical to consider all patients that are not confirmed as formed by an experienced practitioner, the dilation portion of
COVID-19 positive as COVID-19 suspected in the current crisis the procedure and placement of the cannula is possible un-
when performing a tracheostomy. We would recommend PPEs der one cycle of apnoea (Faris et al. Review of Tracheostomy and personal protectieve equipment PPE in COVID-19 patients B-ENT 2020
the ICU or OR theatres, a negative pressure room, if available, ing. A mean of 31 days following onset of symptoms before
should be the standard of care. the PCR in respiratory secretions is negative (69). Furthermore,
despite a negative PCR of respiratory secretions and resolu-
It should be remembered that aerosolization of saliva can oc- tion of symptoms there still remains a risk that the patient
cur even with minor suctioning the pharynx before intubation may still have a sufficient viral load to be infective if a high-risk
(16, 66) so despite these above adaptions, tracheostomy is still AGP (tracheostomy) is performed without suitable PPE (62).
considered a high-risk AGP. As there is no evidence to quanti- Therefore, ideally, the patient should be serially tested until
fy the levels produced in each adapted procedure, no specific COVID-negative before proceeding with a tracheostomy, to
recommendation can be made. The ability to control the lev- maximally reduce the viral load in the aerosol during the pro-
el of aerosol generation in each procedure is likely correlated cedure. However, the patient must still be considered COVID
with the experience of the practitioner. Experienced surgeons/ positive at the time of surgery despite negative tests, and ap-
anaesthetists should, therefore, perform either percutaneous propriate precautions should be taken by all HCWs.
tracheostomy or open tracheostomy in-line with and the ex-
perience/skillset of the local unit/ICU. The concept of shared Best Practice COVID positive Tracheostomies
risk among experienced surgeons/anaesthetists should be ad- Multidisciplinary team (MDT) decision for tracheostomy. Re-
opted. Ideally, having several trained, experienced personnel view indications only proceed in situations where there is a
performing the procedure rather than a small number of in- significant benefit to the patient in terms of overall mortality
dividuals repeatedly. Careful consideration should be made as or morbidity.
to whether surgeons or anaesthetists with co-morbidities/risk
factors such as hypertension, diabetes, and chronic lung dis- Ideally, delay tracheostomies (unless acute airway emergen-
ease should be allowed to perform these procedures, or rather cies) until COVID-negative testing in respiratory secretions.
to delegate these procedures to the next most experienced
members of the medical team. If once COVID positive and now negative still treat as COVID
positive for AGPs as low viral low can persist (62).
When it the best timing for COVID positive tracheosto-
mies? Ideally, delay tracheostomies until stable pulmonary status
Patients with active COVID-19 have high viral titres in na- (desaturations are issues with apnoeic tracheostomies in both
sal mucosal, oral, pharyngeal, and pulmonary secretions (63) open and percutaneous tracheostomies).
which will inevitably produce aerosols if manipulated/operat-
Ideally, negative pressure room (ICU or OR Theatres), Percuta-
ed (16), placing the entire operating room personnel at risk.
neous or Open tracheotomies, dependant on local factors and
Smoke generated from electrocautery of infected tissue and
skills mix.
blood is also a possible additional hazard. Infection concerns
from smoke generation by electrocautery are drawn from ex- AGPs – standard PPE (FFP-3, fit-tested) at a minimum. Alter-
perience from other studies where viral DNA was present in natively, PAPR or combinations of FFP-3 PAPR are preferred
smoke fumes (67, 68). The infectivity of electrocautery smoke for the operating team.
in COVID-19 is not clear, so at this time the use of monopolar
electrocautery is advised against. Advise against performing tracheostomy in FFP-3 respirator
when it is non-fit tested or where there is a fit test failure. The
There is, therefore, a balance between the clinical urgency of procedure should be delegated to colleague with appropriate
tracheostomy and delaying the tracheostomy until the patient PPE.
has negative PCR tests from respiratory secretions, making the
patient less but not always non-infective (62). There are vari- Conclusion
abilities in recommendations. The Canadian guidelines strong-
ly recommend against performing a tracheotomy in COVID-19 We have presented available evidence for several of the cur-
patients who are still infectious regardless of the duration of rent guidelines used by various ENT Head and Neck Societies.
endotracheal intubation (59). American guidelines are less Differences do occur due to lack of evidence for COVID-19.
stringent suggesting that tracheostomy does not take place Many recommendations are based on historical data from the
sooner than 2-3 weeks from intubation in patients with sta- 2003/4 SARS outbreak. Many unanswered questions remain.
ble pulmonary status and ideally negative COVID-19 testing
Disclaimer
(58). The Dutch Society of ORL suggest no surgery within two
weeks and to postpone tracheotomy until patient COVID-19 is The Authors have developed this information to inform its
negative if possible (57). The French Paediatric SFORL guide- members and helpful guidance for its readership. This is based
lines state that very few indications should be maintained and on information available at the time of writing, and the authors
it should induce postponement of non-urgent surgeries of at recognise that new information regarding COVID-19 is comes
least 15 days (53). The ENT-UK guidelines suggest it may be to the public domain every week. Therefore, recommendations
prudent to delay tracheostomy until active COVID-19 disease may change over the coming months. Were lack of evidence
has passed (54, 55). The Belgium Royal Society of ORL recom- exist, the decision has generally been to adopt the more con-
mends a delay if possible and to postpone the procedure until servative (protective) approach for HCWs teams performing
active COVID-19 has passed (61). tracheostomies. The guidance included in this document does
not replace the application of clinical judgement to each indi-
Unfortunately, a purely time-based system is problematic as vidual presentation. The Authors are not liable for the accuracy
critically ill patients may have significantly longer positive test- or completeness of the information in this document.B-ENT 2020 Faris et al. Review of Tracheostomy and personal protectieve equipment PPE in COVID-19 patients
Peer-review: Externally peer-reviewed. 2019 Novel Coronavirus Diseases (COVID-19) - China, 2020. Chi-
na CDC Weekly 2020.
Author Contributions: Concept – C.F., K.D., G.V.H., C.V.L., R.P., K.V., 16. Tran K, Cimon K, Severn M, Pessoa-Silva CL, Conly J. Aerosol gen-
S.M., F.G., N.M., O.M.V.; Design – C.F., O.M.V.; Supervision – C.F., O.M.V.; erating procedures and risk of transmission of acute respiratory
Resources – C.F., O.M.V.; Data Collection and/or Processing – C.F., R.P., infections to healthcare workers: a systematic review. PLoS One
N.M., O.M.V.; Analysis and/or Interpretation – C.F., R.P., N.M., O.M.V.; Lit- 2012; 7: e35797. [CrossRef]
erature Search – C.F., R.P., N.M., O.M.V.; Writing Manuscript – C.F., K.D., 17. Liu Y, Gayle AA, Wilder-Smith A, Rocklöv J.The reproductive num-
G.V.H., C.V.L., R.P., K.V., S.M., F.G., N.M., O.M.V.; Critical Review – C.F., ber of COVID-19 is higher compared to SARS coronavirus. Journal
K.D., G.V.H., C.V.L., R.P., K.V., S.M., F.G., N.M., O.M.V. of Travel Medicine 2020; 27. [CrossRef]
18. Zhao S, Lin Q, Ran J, et al. Preliminary estimation of the basic re-
Conflict of Interest: The authors have no conflicts of interest to de-
production number of novel coronavirus (2019-nCoV) in China,
clare.
from 2019 to 2020: A data-driven analysis in the early phase of
the outbreak. Int J Infect Dis 2020; 92: 214-17. [CrossRef]
Financial Disclosure: The authors declared that this study has re-
19. Preventing Transmission of Pandemic Influenza and Other Viral
ceived no financial support.
Respiratory Diseases: Personal Protective Equipment for Health-
References care Workers: Update 2010, ELL-ACT. Liverman, Editor. 2010, Na-
tional Academies Press: Washington, DC.
1. Wu Z, McGoogan JM. Characteristics of and important lessons 20. Coia JE, Ritchie L, Adisesh A, et al. Guidance on the use of respi-
from the coronavirus disease 2019 (COVID-19) outbreak in China: ratory and facial protection equipment. J Hosp Infect 2013; 85:
Summary of a report of 72314 cases from the Chinese Center for 170-82. [CrossRef]
disease control and prevention. JAMA 2020. [Epub Ahead of Print] 21. England, P.H. Guidance Reducing the risk of transmission of
[CrossRef] COVID-19 in the hospital setting. 2020. Available at: https://www.
2. Wang C, Horby PW, Hayden FG, Gao GF. A novel coronavirus gov.uk/government/publications/wuhan-novel-coronavirus-in-
outbreak of global health concern. Lancet 2020; 395: 470-3. fection-prevention-and-control/reducing-the-risk-of-transmis-
[CrossRef] sion-of-covid-19-in-the-hospital-setting
3. Zhu N, Zhang D, Wang W, et al. A novel coronavirus from patients 22. Siegel JD, Rhinehart E, Jackson M, Chiarello L. Health Care In-
with pneumonia in China, 2019. N Engl J Med 2020; 382: 727-33. fection Control Practices Advisory Committee. 2007 guideline
[CrossRef] for ısolation precautions: preventing transmission of infectious
4. Lu R, Zhao X, Li J, et al. Genomic characterisation and epidemiol- agents in health care settings. Am J Infect Control 2007; 35: 65-
ogy of 2019 novel coronavirus: implications for virus origins and 164. [CrossRef]
receptor binding. Lancet 2020; 395: 565-74. [CrossRef] 23. Yu IT, Li Y, Wong TW, et al. Evidence of airborne transmission of
5. Sun P, Lu X, Xu C, Sun W, Pan B. Understanding of COVID-19 the severe acute respiratory syndrome virus. N Engl J Med 2004;
based on current evidence. J Med Virol 2020.[Epub Ahead of 350: 1731-9. [CrossRef]
Print]. [CrossRef] 24. Christian MD, Loutfy M, McDonald LC, et al. Possible SARS coro-
6. Hui DS, I Azhar E, Madani TA, et al. The continuing 2019-nCoV navirus transmission during cardiopulmonary resuscitation. Emerg
epidemic threat of novel coronaviruses to global health-The latest Infect Dis 2004; 10: 287-93. [CrossRef]
2019 novel coronavirus outbreak in Wuhan, China. Int J Infect Dis 25. Aerosol-generating procedures in ENT. ENT-UK 2020. Available
2020; 91: 264-6. [CrossRef] at: https://www.entuk.org/aerosol-generating-procedures-ent
7. Zhonghua Liu Xing Bing Xue Za Zhi. Novel Coronavirus Pneumonia 26. Hick JL, Barbera JA, Kelen GD. Refining surge capacity: con-
Emergency Response Epidemiology Team. (The epidemiological ventional, contingency, and crisis capacity. Disaster Med Public
characteristics of an outbreak of 2019 novel coronavirus diseases Health Prep 2009; 3(2 Suppl): 59-67. [CrossRef]
(COVID-19) in China). 2020; 41: 145-51. 27. Interim infection prevention and control recommendations
8. Zou L, Ruan F, Huang M, et al. SARS-CoV-2 Viral load in upper re- for patients with suspected or confirmed Coronavirus disease
spiratory specimens of infected patients. N Engl J Med 2020; 382: 2019 (COVID-19) in healthcare settings. CDC 2020. Available at:
1177-9. [CrossRef] https://www.cdc.gov/coronavirus/2019-ncov/infection-control/
9. Rothe C, Schunk M, Sothmann P, et al. Transmission of 2019- control-recommendations.html
nCoV infection from an asymptomatic contact in Germany. N 28. Mansour AA 3rd, Even JL, Phillips S Halpern JL. Eye protection in
Engl J Med 2020; 382: 970-1. [CrossRef] orthopaedic surgery. An in vitro study of various forms of eye pro-
10. Muller MP, Richardson SE, McGeer A, et al. Early diagnosis of tection and their effectiveness. J Bone Joint Surg Am 2009; 91:
SARS: lessons from the Toronto SARS outbreak. Eur J Clin Micro- 1050-4. [CrossRef]
biol Infect Dis 2006; 25: 230-7. [CrossRef] 29. Shoham S, Acuna-Villaorduna C, Cotton M, Hardwick M. Compar-
11. Moore D, Gamage B, Bryce E, et al. Protecting health care work- ison of protection against ocular contamination with disposable
ers from SARS and other respiratory pathogens: organizational eyewear products. Washington Hospital Center 2020. Available
and individual factors that affect adherence to infection control at: http://www.medonyx.com/media/MedStarFullClinicalPoster.
guidelines. Am J Infect Control 2005; 33: 88-96. [CrossRef] pdf
12. Kwan A, Fok WG, Law KI, Lam SH. Tracheostomy in a patient with 30. Workplace Safety & Health Topics. Eye Protection for Infection
severe acute respiratory syndrome. Br J Anaesth 2004; 92: 280-2. Control. CDC 2020. Available at: https://www.cdc.gov/niosh/top-
[CrossRef] ics/eye/eye-infectious.html
13. Li TS, Buckley TA, Yap FH, Sung JJ, Joynt GM. Severe acute re- 31. Lee SA, Grinshpun SA, Reponen T. Respiratory performance of-
spiratory syndrome (SARS): infection control. Lancet 2003; 361: fered by N95 respirators and surgical masks: human subject eval-
1386. [CrossRef] uation with NaCl aerosol representing bacterial and viral particle
14. Wang D, Hu B, Hu C, et al. Clinical characteristics of 138 hospital- size range. Ann Occup Hyg 2008; 52: 177-85. [CrossRef]
ized patients with 2019 novel coronavirus-İnfected pneumonia in 32. NIOSH Guide to the Selection and Use of Particulate Respirators
Wuhan, China. JAMA 2020. (Epub ahead of print). [CrossRef] Certified Under 42 CFR 84. Cincinnati, Ohio, USA: National Insti-
15. Novel Coronavirus Pneumonia Emergency Response Epidemiol- tute for Occupational Safety and Hygiene (NIOSH); 1996. DHHS
ogy Team. The Epidemiological Characteristics of an Outbreak of (NIOSH) Publication no. 96-101.Faris et al. Review of Tracheostomy and personal protectieve equipment PPE in COVID-19 patients B-ENT 2020
33. Rengasamy S, King WP, Eimer BC, et al. Filtration performance of 52. Chee VW, Khoo ML, Lee SF, Lai YC, Chin NM. Infection control
NIOSH-approved N95 and P100 filtering facepiece respirators measures for operative procedures in severe acute respiratory
against 4 to 30 nanometer-size nanoparticles. J Occup Environ syndrome-related patients. Anesthesiology 2004; 100: 1394-8.
Hyg 2008; 5: 556-64. [CrossRef] [CrossRef]
34. Kim JM, Chung YS, Jo HJ, et al. Identification of Coronavirus iso- 53. COVID-19 and ENT Pediatric Otolaryngology during the COVID-19
lated from a patient in Korea with COVID-19. Osong Public Health pandemic. SFORL. 2020.
Res Perspect 2020; 11: 3-7. [CrossRef] 54. Framework for open tracheostomy in COVID-19 patients. ENT-
35. Grinshpun SA, Haruta H, Eninger RM, Reponen T, McKay RT, Lee UK 2020. Available at: https://www.entuk.org/sites/default/files/
SA. Performance of an N95 filtering facepiece particulate respi- files/COVID%20tracheostomy%20guidance_compressed.pdf
rator and a surgical mask during human breathing: two pathways 55. Guidance for Surgical Tracheostomy and Tracheostomy Tube Change
for particle penetration. J Occup Environ Hyg 2009; 6: 593-603. during the COVID-19 Pandemic. ENT-UK 2020. Available at: https://
[CrossRef] www.entuk.org/tracheostomy-guidance-during-covid-19-pandemi
36. McMahon E, Wada K, Dufresne A. Implementing fit testing for 56. Current ENT Italian Guidelines for Tracheostomy in COVID-19.
N95 filtering facepiece respirators: practical information from a SIOeChCF 2020. Available at: https://www.sioechcf.it/riassun-
large cohort of hospital workers. Am J Infect Control 2008; 36: to-linee-guida-la-tracheostomia-in-pazienti-affetti-da-covid-19/
298-300. [CrossRef] 57. Recommendations for performing tracheotomy during COVID-19
37. Lee MC, Takaya S, Long R, Joffe AM. Respirator-fit testing: does pandemic. Keel-Neus-Oorheelkunde en Heelkunde van het
it ensure the protection of healthcare workers against respira- Hoofd-Halsgebied 2020. Available at: https://www.kno-leden.
ble particles carrying pathogens? Infect Control Hosp Epidemiol nl/leden/public/doc/2020-04-06%20-%20Aanbevelingen%20
2008; 29: 1149-56. [CrossRef] rondom%20uitvoeren%20tracheotomie%20tijdens%20
38. Tien HC, Chughtai T, Jogeklar A, Cooper AB, Brenneman F. Elec- COVID-19%20pandemie.pdf
tive and emergency surgery in patients with severe acute respira- 58. Tracheotomy Recommendations During the COVID-19 Pan-
tory syndrome (SARS). Can J Surg 2005; 48: 71-4. demic, in AAO-HNS Practice guideline. Surgery, AAO-HNS 2020.
39. Roberts V. To PAPR or not to PAPR? Can J Respir Ther 2014; 50:
Available at: https://www.entnet.org/content/tracheotomy-rec-
87-90.
ommendations-during-covid-19-pandemic
40. Reusable respirator facepieces and powered air purifying respi-
59. Recommendations from the CSO-HNS Taskforce on Perfor-
rator systems (PAPRs) in the health care environment: consider-
mance of Tracheotomy During the COVID-19 Pandemic. Sur-
ations for use. 3M Technical Data Bulletin 2003; #160.
gery, CSO-HNS 2020 Available at: https://www.entcanada.org/
41. Roberge RJ. Evaluation of the rationale for concurrent use of N95
wp-content/uploads/COVID-19-Guidelines-CSOHNS-Task-
filtering facepiece respirators with loose-fitting powered air-pu-
Force-Mar-23-2020.pdf
rifying respirators during aerosol-generating medical procedures.
60. Guidance for ENT surgeons during the COVID-19 pandemic. Sur-
Am J Infect Control 2008; 36: 135-41. [CrossRef]
gery, ASO-NHS 2020 Available at: www.asohns.org.au/about-us/
42. Assigned Protection Factors (APF) for 3M™ Hoods and Helmets.
news-and-announcements/latest-news?article=78
3M Personal Safety Division 2019.
61. COVID-19/ SARS-CoV-2 PRECAUTIONS FOR ENT’s. Surgery,
43. Roberge MR, Vojtko MR, Roberge RJ, Vojtko RJ, Landsittel DP.
RBSO-CS 2020. Available at: https://www.orl-hno.ch/filead-
Wearing an N95 respirator concurrently with a powered air-puri-
min/user_upload/Dokumente/News/B-ORL_CoVid-19_precau-
fying respirator: effect on protection factor. Respir Care 2008; 53:
tions_24-03-20__.pdf
1685-90.
62. Lippi G, Simundic AM, Plebani M. Potential preanalytical and an-
44. Derrick JL, Gomersall CD. Surgical helmets and SARS infection.
Emerg Infect Dis 2004; 10: 277-9. [CrossRef] alytical vulnerabilities in the laboratory diagnosis of coronavirus
45. Ahmed N, Hare GMT, Merkley J, Devlin R, Baker A. Open trache- disease 2019 (COVID-19). Clin Chem Lab Med 2020. [Epub Ahead
ostomy in a suspect severe acute respiratory syndrome (SARS) of Print] [CrossRef]
patient: brief technical communication. Can J Surg 2005; 48: 68- 63. Wang W, Xu Y, Gao R. Detection of SARS-CoV-2 in different
71. types of clinical specimens. JAMA 2020. (Epub ahead of print)
46. Handbook of COVID-19 Prevention and Treatment. 2020: The First [CrossRef]
Affiliated Hospital, Zhejiang University School of Medicine Available at 64. Ai T, Yang Z, Hou H. Correlation of chest CT and RT-PCR testing in
http://www.zju.edu.cn/english/2020/0323/c19573a1987520/page. Coronavirus disease 2019 (COVID-19) in China: A report of 1014
htm cases. Radiology 2020. [Epub Ahead of Print] [CrossRef]
47. Wax RS, Christian MD. Practical recommendations for critical care 65. Colpaert C, Cox T, de Varebeke SPJ, et al. Is percutaneous trache-
and anesthesiology teams caring for novel coronavirus (2019- otomy safe in the context of anticoagulant therapy. B-ENT 2019;
nCoV) patients. Can J Anaesth 2020; 67: 568-76. [CrossRef] 15: 173-78.
48. Loeb M, McGeer A, Henry B, et al. SARS among critical care nurses, 66. Raboud J, Shigayeva A, McGeer A, et al. Risk factors for SARS trans-
Toronto. Emerg Infect Dis 2004; 10: 251-5. [CrossRef] mission from patients requiring intubation: a multicentre investiga-
49. Booth CM, Stewart TE. Communication in the Toronto critical tion in Toronto, Canada. PLoS One 2010; 5: e10717. [CrossRef]
care community: important lessons learned during SARS. Crit 67. Christie D, Jefferson P, Ball DR. Diathermy smoke and human
Care 2003; 7: 405-6. [CrossRef] health. Anaesthesia 2005; 60: 632. [CrossRef]
50. Scales DC, Green K, Chan AK, et al. Illness in Intensive Care Staff 68. Okoshi K, Kobayashi K, Kinoshita K, Tomizawa Y, Hasegawa S,
after Brief Exposure to Severe Acute Respiratory Syndrome. Sakai Y. Health risks associated with exposure to surgical smoke
2003; 9: 1205-10. [CrossRef] for surgeons and operation room personnel. Surg Today 2015; 45:
51. Wei WI, Tuen HH, Ng RW, Lam LK. Safe tracheostomy for patients 957-65. [CrossRef]
with severe acute respiratory syndrome. Laryngoscope 2003; 113: 69. Chen J, Qi T, Liu L, et al. Clinical progression of patients with
1777-9. [CrossRef] COVID-19 in Shanghai, China. J Infect 2020; 80: e1-e6. [CrossRef]You can also read
